This invention relates generally to motor vehicle tow hitches and more particularly concerns a signal device capable of providing an early indication of a tow hitch failure.
Typically, a ball-and-socket hitch is used to connect a towed vehicle to a towing vehicle. The ball is mounted at the rear of the towing vehicle and the hitch is a wishbone-shaped tow bar with a socket at the neck of the wishbone. The ball-and-socket provides a generally universal range of motion at the towing vehicle to accommodate changes in direction and incline. The outer ends of the wishbone are coaxially pivotally connected to the front of the tow vehicle to accommodate changes in incline.
In operation, a variety of failures can occur in the hitch assembly. The ball it mounted on the towing vehicle. The socket is seated over the ball. The outer ends of the tow bar are pivoted. The pivots are mounted on the front of the towed vehicle. In addition, the towing vehicle, the tow bar and the towed vehicle all include welded or otherwise joined subcomponents. Failure at any connection point in the hitch assembly could result in loss of control or even complete loss of connection with the towed vehicle.
Presently, brake lock systems exist which are activated only if the hitch or the towed vehicle has separated from the towing vehicle. These systems could provide an indication of the failure to the towing vehicle occupants, but only subsequent to the separation.
It is, therefore, an object of this invention to provide a signal device which alerts the occupants of the towing vehicle upon occurrence of any condition in the hitch assembly which allows the distance from the rear center of the towing vehicle to the front center of the towed vehicle to exceed a threshold. Another object of this invention is to provide a signal device which uses the battery of the towing vehicle to power its indicator circuit. A further object of this invention is to provide a signal device which uses the horn of the towing vehicle as an audible indicator of hitch failure. Yet another object of this invention is to provide a signal device which is adaptable for use with a variety of towing vehicles. It is also an object of this invention to provide a signal device which is adaptable for use with a variety of towed vehicles.
In accordance with the invention, a signal device is provided which is capable of giving an early indication of a failure of a typical ball-and-socket hitch. Such hitches have a wishbone-shaped tow bar. The tow bar is universally pivotally connected at its socket to the ball which is mounted on the rear of the towing vehicle. The tow bar is coaxially pivotally connected at its outer ends to the front of the towed vehicle. The device includes a break-away switch mounted on a first bracket. The first bracket is adapted to be mounted on the rear of the towing vehicle with the actuating member of the switch positioned substantially immediately above the ball of the hitch and at a rear of the switch. A second bracket is mounted on the front of the towed vehicle at substantially the midpoint of the pivotal axis between the tow bar outer ends. A cable is connected between the actuating member and the second bracket. The cable has a length such that, when the distance between the switch and the second bracket exceeds a predetermined threshold, the cable pulls the actuating member rearwardly to actuate the switch. Preferably, a clamp mounted on the second bracket allows adjustment of the length of the cable between the switch and the second bracket to set the predeterminable threshold. An indicator circuit in the towing vehicle is actuated in response to operation of the breakaway switch. The indicator circuit provides an audible and/or a visual signal upon actuation. Preferably, adapters connect the breakaway switch to the horn circuit of the towing vehicle so that the towing vehicle horn is activated in response to operation of the breakaway switch.